1. Field of the Invention
This invention pertains to an apparatus for improving the performance of flashlights by providing a longer lighting life and higher efficacy. More particularly, the invention relates to improving flashlight performance by replacing a standard incandescent miniature lamp found in conventional flashlights with a light emitting diode (LED).
2. Discussion of the Art
Conventional flashlights use miniature incandescent lamps as a light source. Incandescent lamps generally require filaments and cathode tubes for operation. Filament lamps and cathode tubes, although widely used and commercially successful, are relatively fragile and require careful handling. Components of these lamps often break, even when receiving only a small shock. In addition, filament lamps have a relatively short operating life, thereby giving users the trouble of frequently replacing a burned out bulb and tube shaped portions. Furthermore, filament lamps are not the most economical. These lamps have numerous components making them relatively expensive to manufacture. Finally, filament lamps have a relatively high power consumption. These characteristics have led researchers to study new ways to provide more efficient lighting.
Light emitting diodes (LEDs) have made significant advances in providing a light source having increased performance since their inception in the 1960's. In the 1980's, red-emitting AlGaAs LEDs were developed, such devices being more energy efficient and longer lasting producers of red light than red-filtered light sources in various applications, such as automotive brake lights. Moreover high-efficiency LEDs have been developed and are commercially available in the blue and blue/green wavelength range based on, for example, InGaN and AlGaN semiconductor materials.
The advent of UV and blue LEDs allowed the possibility to generate white light from an LED by applying luminescent phosphor materials on top of the LED. This layer of phosphor partially transforms the UV or blue light into longer wavelengths, e.g. yellow light. Successful implementation of such a device is dependent upon the efficient conversion of UV/blue light into visible light of the desired wavelength and the subsequent efficient extraction of the generated visible light from the device. However, the first commercially available white light LED systems were not competitive with standard light sources with respect to performance, since the phosphor layer only partially transformed the UV or blue light into longer wavelengths. Not until recently have devices and methods been developed for efficiently converting UV/blue light into visible light.
White-light LED systems provide significant benefits over traditional incandescent lamps. As white light producing LED systems become more refined and efficient, a need exists to expand the use of such systems into others areas, such as the art of flashlights. As already discussed, current incandescent lamps used for flashlights have multiple components (increasing the cost to manufacture), are fragile, and have a relatively short operating life. Constructing a flashlight with an LED as its light source would alleviate most, if not all, of the foregoing problems. To date, no device exists which adequately utilizes an LED system in flashlights. Therefore, it would be advantageous to provide an LED light source for flashlights which replaces the traditional filament lamp with an LED light source.